Process of making halftone printing plates



April 7, 1925.A 4153.25596 R. J. HASSARD ET AL PROCESS OF MAKING HALFTONE PRINTING PLATES Filed Sept. 23. 1921 l 5 Y 1 ve 4 ffl/sing Sheet, 3 pac/ng glass.

'tired pleite 5 Vliegatue l \Re A /oleNEy Patented Apr.- 7, 15925.

miran STA .TES-.PA

fil-,532,696

TENT OFFICE..

ROBERT J. nessnnn, OF BROOKLYN, Amos-'11. summe, or. Anvnmm, AND yrimini T. rownns, or DOUGLASTON MANOR., NEW YORK, AssIoNOns- To POWERS PHOTO- ENGRAVING COMPANY, F NEW YORK,'N. Y., A CORPORATION OF` NEW YORK.

Pnoonss or MAKING'HALFTONE PRINTING PLATES.

Application tiledl September 23, 1921. Serial No; 502,756.

To all whom t may concern.'

Be it known that we, ROBERT J HAssARD,

a citizen of the .United States, residing atl p No.' 2526 Gates Avenue, Brooklyn, New

York, Amos H. SPALDINO, a citizen of thel United States residing at Arverne, Long Island, New lork, and FRANK T. Powers,

a citizen of the United States, residing at Douglaston Manor, Long Island, New York, lo have made certain new and useful Improvements in Processes of Making Halftone Printing Plates, of which the following isa specification.

The inventioii relates to a process for making half-tone printing plates, and more particularly to a process for making such plates wherein the shadows and preferably also darker intermediate tones are brought out or emphasized during the plate making process, and without subsequent handwork'- representthe original in all its tone values.

or mechanical deformation of the plate.

Objects and advantages of the invention will be set forth in part hereinafter and in part will/be `obvious herefrom, or may be learned' by practice with the invention, the

same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novelsteps no and processes herein shown and described.

The accompanying drawing is diagrammatic in character, but serves to illustrate certain steps in the invention, said drawing taken together with the description serving to illustrate in an exemplary manner the plate of. Fig. 2 re-sensitized for the second;

. exposure;

ing the photo-mechanical Fig. a shows the re-exposure-Of the re-sen' tive as was used in'Fig..1; and

Fig. -5 shows the finished printing plate after it has been developed after the exposure shown in Fig. 4. v

It will be understood that all of the drawings are diagrammatic in character, and do not at all actually represent or picture the actual printing plateor the actual instrumentalities employed therewith or thereon, as in the actual operation 'the results are such as .to be incapable of exactillustration in a drawing of this kind.-

By the process of the present invention there is kproduced a printing plate designed to give under varying conditions, and designed'for different classes of work, such for example as different kinds of paper stock .or different kinds of printing, a printing impression which will properly and accurately For many kinds of work it is necessary to emphasize, or especially bring out, the shadows and sometimes also the .deeper or darker intermediate tones in the printing plate, so that thev printing impression may correctly or adequately represent the'tone values of the original.

B the present invention, theshadows and preferably also the deeper middle tones arevbrought into greater relief in the printing plate than the whites and the lighter intermediate tones, without mechanical deformation of the plate and without extra manual work, the desired resultbeing effected durproduction of the plate. i In the present preferred manner of practicing the invention, and defining the process broadly, the printing plate of copper or zinc, or other suitable/material, is sensitized and is exposed to the light through a screen gure negative, the light being diffused, or' equivalently acted upon.4 to prevent the smallestA screen figures, which represent -the whites and the lighter intermediate tones of the original, from mak-ing an impression upon the sensitized surface of the printing plate, while on the other hand the shadows, and preferably the deeper intermediate.

sitized printing plate under the same negal atthe edges of the relief in the plate.v To

i bis) obviate the possibilit of this tendency or i condition obtaining 1n the finished plate,

after the plate has been cleaned from the first etching, as just described, the cleaned plate is put back in the etching solution and is then washed thoroughly. This plate is then re-sensitized and is exposed to the light through the same negative, this time without the diused action of the light, and all the tones and values of the screen figure negative are impressed on the sensitized surface of the plate in their true relation or relative value. The plate is then developed and etched, preferably, in the usual man ner, and will have the shadows and deeper intermediate tones in slightly greater relative relief than the whites and the lighter intermediate tones. It will be understood, of course, that three or more successive exposures may be made, instead of the two described, While still utilizing the principle of our invention.

Referring now infdetail to the present preferred form of carrying out the invention, a screen ligure negative, which may be an ordinary half-tone negative, is u sed, such. n egative vbeing made from any sultable orlginal, such as'a photograph, in the usual manner. This negative may be of any kind, that'ls, one having fairly' strong contrast between the .lightsand shadows: This gives a relatively small dot or other` screen figure in the highest lights The printing plate, that is, the plate to be made-into a printin plate, will usually be of copper -or zinc, an the surface thereof is sensitized in the usual manner, asfor instance by a coating of chromated albumen.

We prefer to employ the method of direct action or contact of the screen-figure negative upon the sensitive plate, which is approximately similar to the usual .contact lmethod except that they are preferably spaced apart to securepthe diffusing action of the light.

: As illustrated, in Fig.1, a spacing sheet or member 3 is laid upon the light-sensitive surface 2 of the copper. or other plate 1. The spacing sheet 3 is usually made of clear Celluloid, which is highly transparent and which has the necessary or desirable flexibility. This'sheet3 is used primarily as a spacing medium.

The preferred form of the diffusing agent or instrumentality is a thin sheet 4 of parchment paper, which 'is laid over the spacing sheet 3. The screen-ligure negative 5 is placed' over the diffusing sheet 4, and the sensitized surface 2 is exposed to the action of the light 6, in the proper manner, position and for a proper period of time.

The diffusing sheet 4 diffuses the light so that the dots or screen figures, especially the smaller ones, make no impression by the light action on the sensitized Asurface 2 vof the plate l. The result is that such dots or other screen figures do not appear on the plate after the first development, `which follows on the exposure just described, but

termediate tones appear on the plate as the result of this exposure and development.

The plate after being so exposed is developed and etched preferably, in the usual manner, and with the usual agents, as for example, a ferrie chlorid solution for a copper plate or a nitric acid solution etch for a zinc plate. The plate is preferably prepared with an ink top, that is, the plate is rolled up with a resistant ink preliminarily to the etching, and the etching is usually relatively the plate -is cleaned.

The printing plate as so developed is then re-sensitized, preferably with.l the ordinary enamel solution, this condition of the plate slight or shallow, and thereafter y being represented diagrammatically in Fig. Y

3 of the drawings.

The plate as so re-sensitized, with the' light-sensltive layer 8 overlaying the de' veloped surface 7, is .given a contact ex posure to light throughthe negative 5. The nature of the usual enamel solution is such that there is close contact betweenl lthe image-bearing surface of the negative 5 and the sensitized surface 8 of the platein all their parts, and this time a sharp image of` all parts of the screen figure surface of the negative is impressed by the lightaction upon the sensitive surface 8 of the plate in `their true relative tone values. The negative 5 will of course be inregistei" both times. l

The plate 1-as so re-exposed, is developedl in any suitable manner and preferably etched in the usual manner for half-tone plates.l The plate is then 'cleaned' and is Iready for printing.

Such a printing plate-as the result of the photo-mechanical process has a double refj lief, as it has throughout a screen-gure relief corresponding in its various parts to' the relative tone values or degrees'of opacit of the. screen-figure negative of theorigina but underlying this it has a relief and depression corresponding broadly to the lshadows and darker undertones, which will bring them up during the printing in. the PIOpeI relation.

iso

80 only/the solid shadows and the deeper in- Lacasse llt will be understood that variations may be made from the exact manner of carrying out the process and from the exact instrnmentalities herein shown and described, Within the scope of the accompanying claims, and Without departing from the principles oi the invention.

lWhat We claim is l. rlhe process of making printing plates which comprises sensitizing a plate, impressing on' the sensitized late by lioht action the shadows and dar t intermedlate tones only of an original, developing and etching the plate, resensitizing the plate, impressin on the re-sensitized plate by light vaction al the tones of the original, and developing and etching the plate.

2. rlhe process of makingprinting plat-es which comprises sensitizing a plate, impressing on the sensitized late by light action the 'shadows and dartv intermediate tones only of an original, developin` and etching late, impressing on the re-sensitized plate by light action all the tones of the original in their actual relative values, and developing and etching the plate.

3. The process `.of making printing plates which comprises sensitizing a plate, impressing on the sensitized plate by light action the shadows only of an original, developing and etching the plate, re-sensitizing the late, impressing on the ire-sensitized plate y light action allthe tones of the original, and developingpand etching the plate.

4. rilhe process of making printing plates which comprises sensitizing a plateg impressing on the sensitized plate by .light action the shadows only of an original, developing and etching the plate, re-sensitizing the plate, impressing on the re-sensitized plate by light action all the tones of the original in their actual relative values, and developing and etching the plate. i

5. The process of making printing plates which comprises sensitizing a plate, ex osing the plate to light action throng a screen-figure negative While diffusing the light so as toprevent the light action of the whites and lighter intermediate tones on the plate While impressing thereon by the light action the shadows of the original, developing and etching the plate, re-sensitizing the plate, impressing lon the re-sensitized plate by light action all of thetones of the original, and developing and etching the plate. *n Y o. 'Ehe process of making printing plates which comprises sensitizing a plate, exposing the plate to light action through a screen-ligure negative While didusing the light so as to prevent the light action of the 'whites and lighter'intermediate tones on thev plate While impressing thereon'by the light action the sinaijlovvs and dark intermediate tones of the original, developing and etching the plate, re-sens'itizing the plate, im-

pressing' on the rie-sensitized plate by light action all of the tones ot the original, and developing and etching the plate.

7. The process of making printing plates which comprises sensitizing a plate, exposing the plate to light action through a screen-figure negative while diusing the light so as to prevent the light action of the t5 whites and lighter intermediate tones on the plate. While impressing thereon by the light action the shadows of the original, developing and etching the plate, re-sen'sitizing the plate, impressincr on the re-sensitized plate by light actionall of the tones of the original in their actual tone values, and developing and etching the plate.

8. The process of making printing plates which comprises sensitizing a plate, exposing the plate to light action through a screen-ligure negative. While diffusing the light so as to prevent the light action of the Whites and lighter intermediate tones on the plate'while impressing thereon by the light action the shadows and dark intermediate -tones of the original, developing and etch- Iscreen-ligure negative While diffusing the light so as to prevent the light action of the Whites and lighter intermediate tones on the plate while impressing thereon by the light action the shadows of the original, developing and etchino the plate, re-sensitizing the plate, exposing the re-sensitized plate to light through the same screen-figure negative without diffusion of the light to impress on the plate all the tones of the original, and developing and etching the plate.

10. rlhe process of making printing plates which comprises sensitizing a plate, exposing. the plate to light action through a screen-figure negative While diffusing the 315 light so as to prevent the light action of the whites and lighter intermediate tones on the pla-te While impressing thereon by the light action the shadows and dark intermediate tonesot the original, developing and etcli- 120 ing the plate, re-sensitizing the plate, exposing there-sensitizedplate toI light through the same screen-figure negative Without ditfusion of the light to impress on the plate all the Vtones of the original, and developing H5 and etching the plate. il. The p-rocess of making printing plates ywhich comprises sensitizing a plate, exposing the plate to light action through a light so as to prevent'the light action of the W ites and lighter intermediate tones on the plate while impressing thereon by the light action the shadows of the original, developing and etching the plate, re-sensitizing the.

plate, exposing the re-sensitized plate to light thropgh the same screen-figure nega'- tive without diffusion of the light to impress on the plate-all the tones of the original in' tive without diffusion of the light to impress on the plate all the tones of the original in their actual tone values, and developing and etching the plate. l

13. The process of making printing plates which comprises sensitizing a plate, exposing the sensitized plate to light action through a screen-figure negative, with a dit'- using sheet interposed therebetween, so as to. prevent the light action of the whites and light intermediate tones on the plate while impressing thereon by the light action the shadows of thel original, developing and etching the plate, re-sensitizing the plate, exposing the re-sensitizcd plate to light through the same screen-figure negative in close contact with the plate to impress on the plate all the tones of the original, and

. developing and etching the plate.

14. The process of making printing plates which comprises sensitizing a plate, exposing the sensitized plate to light action through a screen-figure negative, with a diffusing sheet interposed therebetween but lspaced away from the sensitized surface oi' thel plate, so as to prevent the light action of the whites and light intermediate tones on the plate while impressing thereon by the light action the shadows of the original, developing and etching the plate, re-sensitizing the plate, exposing the re-sensitized plate to light through the same screen-ligure negative in close contact with the plate to impress on the plate all the tones of the original, and developing and etching the plate.

15. The process of making printing plates which comprises sensitizing a plate, exposing -the sensitized plate to light action through a screen-figure negative, with a diffusing sheet interposed therebetween, so as theplate to impress on the plate all the tones of the original, and developing and etching the plate.`

The process of making printing plates which comprises sensitizing va plate, impressing on the sensitized plate by light action the shadows and dark intermediate tones only ot an original, developing and etching the plate, cleaning the plate andv subjecting the clean" plate to the etching solution, re-sensitizing the plate, impressing on the re-sensitized plate by light action all the tones of the original, and developing and etching the plate.

17. The process of making printing plates which comprises sensitizing a plate, impressing on the sensitized plate by light action the shadows only of an original, developing and etching the plate, cleaning the plate and subjecting the clean plate to the etching solution, re-sensitizing the plate, impressing on the re-sensitized plate by light action all the-tones of the original, and developing and etching the plate.

18. The process of making printing plates .which comprises sensitizing a plate, exposing the plate to light action through a screen-figure negative while diffusing the light so as to prevent the light action of the whites and lighter intermediate tones on the plate while impressing thereon by the light action the shadows of the original, develop- 'ing and etching the plate, cleaning the plate and subjecting the clean plate to "the etching solution, re-sensitizing the plate, impressing on the re-sensitized plate by light action all of the tones of4 the original, and ldeveloping and etching the plate.

1 9. rlhe process'of making printing plates which comprises sensitizing, exposing, developmg and etching a plate, cleaning the plate and subjecting the clean plate to the ln testimony whereof we have signed our I l names to this specification.'

ROBERT J. -I-IASSARD. AMOS H. SPALDING. FRANK T. POWERS. 

